DESCRIPTION: The Neuropathology Core is designed to provide technical expertise and services relating to the histologic assessment and quantitation of demyelination within the CNS to complement methods of gross clinical assessment of disease for all members of the Program Project Grant (PPG). The overall goal of the PPG is to elucidate the cellular and molecular mechanisms of induction and progression of Theiler's virus induced demyelinating disease. A critical feature is the ability to assess and quantitate gross CNS pathology and demyelination under various disease conditions and in animals undergoing various regulatory treatments. The use of Dr. Mauro Dal Canto's longstanding expertise in neuropathology will allow uniform analysis and ready comparison among the different projects within the PPG and provide a focal point for collaboration among the members of the PPG. This Core will perform two vital functions for the execution of the PPG as a cohesive unit: Aim 1 - Histopathologic analysis of CNS demyelination and inflammation. Aim 2 - Preparation of organotypic CNS slice cultures for the assessment of the demyelinating capacity of various glial cell populations activated with various pro-inflammatory cytokines or directly by TMEV infection.